酸性磷类萃取剂在硫酸介质中对Y(Ⅲ)的协萃机制研究

对HDEHP(H2A2),HEH/EHP(H2B2),Cyanex272(H2L2)萃取剂在硫酸介质中单独以及HDEHP-HEH/EHP和HDEHP-Cyanex272混合萃取剂萃取稀土元素Y(Ⅲ)的机制进行了研究. 研究发现,单独采用HDEHP和HEH/EHP萃取Y(Ⅲ)时,SO2-4参与了反应,造成反应过程中放出的H 个数随萃取剂浓度的变化而变化,对于单独采用Cyanex272萃取Y(Ⅲ)的过程中则是OH-参与了反应. 计算了混合萃取剂萃取Y(Ⅲ)的协萃系数(R),当水相平衡pH=1.2时,HDEHP和HEH/EHP混合萃取体系与HDEHP和Cyanex272混合萃取体系萃取Y(Ⅲ)的R分别为27.68和48.99,并且协萃系数随水相平衡pH的升高而增加. 确定了在HDEHP和HEH/EHP混合萃取体系中的协萃反应并计算了反应的平衡常数及萃合物形成反应的稳定常数,反应机制为阳离子交换反应.     

2-乙基己基膦酸单2-乙基己基酯和二(2-乙基己基)磷酸从硫酸介质中协同萃取Ce(Ⅳ)的研究

研究了用2-乙基己基膦酸单-2-乙基己基酯(HEH/EHP,P507)和二(2-乙基己基)磷酸(HDEHP,P204)从硫酸介质中协同萃取Ce(Ⅳ)的机制.结果表明:在HEH/EHP的摩尔分散在0.6时,体系的协萃系数最大.Ce(Ⅳ)以Ce(SO4)0.5HL2A2的形式被萃人有机相,协萃反应为阳离子交换机制.同时还得到了HEH/EHP和HDEHP从硫酸介质中协同萃取Ce(Ⅳ)时,体系的平衡常数及热力学函数如△G,△H和△S等.     

2-乙基己基膦酸单(2-乙基己基)酯萃取稀土元素机理的研究 III.高浓度稀土元素(III)在H~+(HNO_3,HCl)-H_2O-HEH(EHP)-煤油体系中的分配及萃取反应

2-乙基己基膦酸单(2-乙基己基)酯[HEH(EHP),HL]是萃取分离稀土元素的有效萃取剂.作者及马恩新等研究了HEH(EHP)萃取低浓度稀土元素的平衡反应.Lenz等认为二(2-乙基己基)磷酸(HDEHP)萃取高浓度Nd(Ⅲ)和Sm(Ⅲ)时,ClO_4~-及NO_3~-参与萃取反应.定量研究HEH(EHP)从矿物酸溶液中萃取高浓度稀土元素(Ⅲ)的平衡规律及萃取反应具有实际意义,有关这方面的研究尚未见报道. 本文结合分离工艺,系统地研究了高浓度稀土元素在H~+(HNO_3,HCl)-H_2O-1.50FHEH(EHP)-煤油体系中的分配平衡,通过IR、NMR及平衡有机相中NO_3~-和Cl~-浓度的定量测定,提出了低酸度下不同稀土浓度的萃取反应.     

HEH(EHP)-煤油-HCl-RECl_3体系单一稀土的萃取平衡

HEH(EHP)(2-乙基己基膦酸单2-乙基己基酯)作为萃取剂,萃取分离稀土的研究结果表明,HEH(EHP)有较高的分离系数,是一种有效的稀土分离萃取剂。为深入了解HEH(EHP)对稀土元素的萃取性能,以便提供萃取分离工艺的设计参数,我们研究了HEH(EHP)-煤油-HCl-RECl_3体系在不同初始条件下,15个单一稀土的萃取平衡数据,     

二（2,4,4—三甲基戊基）膦酸萃取稀土离子

2-乙基己基膦酸单2-乙基己基酯(HEH/EHP)是目前稀土湿法冶金工业中应用最广泛的萃取剂。但存在重稀土离子反萃取酸度高,某些中、重稀土离子对的分离系数小、选择性不高等缺点。所以研究优于HEH/EHP的新萃取体系已引起人们极大的关注。近年来发现,二(2,4,4-三甲基戊基)膦酸(HBTMPP,HL)有可能是萃取稀土元素的有效萃取剂。由于其分子中不含酯氧原子,使得它的pK。值比HEH/EHP高。因此,用HBTMPP萃取稀土及其它高价     

PMBP与HEH[EHP]对Fe（Ⅲ）的协同萃取

本文研究了1-苯基-3-甲基-4-苯甲酰基吡唑酮-5(PMBP,HL)和2-乙基己基膦酸单(2-乙基己基)酯(HEH[EHP],HA)的二甲苯溶液对盐酸介质中Fe(Ⅲ)的AA类协同萃取。用斜率法确定二元协萃配合物组成为FeL_2A,计算了协萃反应的平衡常数和热力学函数,讨论了协萃配合物的IR和~1H NMR谱。     

HBTMPTP与伯胺N1923对稀土元素(Ⅲ)的协同萃取

研究了二（2，4，4-三甲基戊基）单硫代膦酸（HBTMPTP，HL）和伯胺N1923的正己烷溶液从硫酸介质中对稀土元素（Ⅲ）的协同萃取．并以La（Ⅲ）为例，用斜率法、恒摩尔法和饱和法确定了协萃配合物的组成为（RNH3）3L2La（SO4）2，计算了协萃配合物的生成常数及热力学函数，观测了协萃配合物的IR谱．     

HEH(EHP)萃取柱色谱法从共存元素中分离稀土元素及其应用

2-乙基己基膦酸单2-乙基己酯(HEH(EHP))是一种国内应用较为广泛的酸性磷类萃取剂,以往多侧重于分离稀土的研究,对稀土与非稀土元素的分离则报导较少。苏联Ромацива用HDEHP萃取柱色谱法分离和测定了合金钢中稀土,由于分离不完全,只能测定铈和钐。HEH(EHP)萃取柱色谱法广泛地应用于稀土分离,若同时能分离共存的非稀土元素,无疑是很有意义的。本文提出用磺基水杨酸(SSal),葡萄糖酸(Glu)和抗坏血酸     

P204-P507-H2SO4体系萃取稀土元素的研究

对P204与P507混合萃取剂在硫酸介质中萃取分离Nd和Sm的行为进行了研究。重点考察了在硫酸介质中,P204添加一定量P507对稀土萃取能力、反萃性能以及Nd-Sm分离效果的影响。测定了不同比例的混合有机相在不同平衡酸度下的Nd,Sm分配比以及协同系数,并得到了相应条件下的Sm/Nd分离系数。试验结果表明,P204与P507混合体系在硫酸介质中萃取分离Nd,Sm时存在不同程度的正协同效应。     

氯化稀土与丙氨酸配合行为的研究

用半微量相平衡方法研究了SmCl~3-Ala-H~2O三元体系在25℃时的溶解度。结果表明体系中形成了两种配合物: Sm(Ala)~2Cl~3.3H~2O和Sm(Ala)~3Cl~3.3H~2O,合成了RE(Ala)~3Cl~3.3H~2O(RE=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy),RE(Ala)~2Cl~3.nH~2O(RE=La, Ce, Pr, Nd, Sm, n=3; RE=Ho, Yb,Y, n=4)与RE(AlA)Cl~3.6H~2O(RE=Eu, Gd,Tb, Dy, Ho, Yb, Y)二十四种固体配合物, 用化学分析、IR、UV、X射线分析及TG-DTG对配合物进行了表征, 发现了RECl~3与Ala形成配合物的规律性。     

Activity Coefficients of di-(2-ethylhexyl) Phosphoric Acid in Select Diluents

This work characterizes the non-ideal behavior of the solvent extraction agent di-(2-ethylhexyl) phosphoric acid (HDEHP), constituting one piece of an effort to develop increasingly accurate models of advanced fuel separation processes such as TALSPEAK. Robust models are particularly important for processing high-level radioactive material in order to minimize the generation of secondary waste and to ensure reliable process control. Here, vapor pressure osmometry (VPO) data on binary solutions of HDEHP in toluene, dodecane, or cyclooctane yields the activity coefficients for each component after analysis. Initially, diluent activity data is obtained using the VPO results and then modeled using Scatchard-Hildebrand theory to provide the activity coefficients for HDEHP.     

X-Ray Photoelectron Spectroscopy Analysis of Di-(2-ethylhexyl) Phosphoric Acid Activated Membranes

Surface chemical characterization of activated composite membranes, which consist of a polyamide/polysulfone support containing different amounts of di-(2-ethylhexyl) phosphoric acid as carrier, was performed by X-ray photoelectron spectroscopy (XPS) in order to obtain information about the nature of the chemical bonding between the carrier and the membrane top layer. XPS spectra of the top layer of the polymeric support (polyamide) show bands in the C 1s, N 1s, O 1s, and P 2p regions. The N 1s and O 1s signals of the polyamide layer were asymmetric and could be deconvoluted in two peaks that correspond to the coexistence of free and hydrogen bonded polyamide. To support this assignment, primary amides such as benzamide and n-butyramide, which can associate themselves forming hydrogen bonding, and a tertiary amide, N-benzoyl morpholine, unable to form hydrogen bonding, were also studied by XPS. The N 1s asymmetric signals of benzamide and n-butyramide were deconvoluted in two peaks due to the coexistence of free and hydrogen bonded species, while the N 1s signal of N-benzoyl morpholine is symmetric and corresponds to the existence of free amide alone. As a result of the addition of di-(2-ethylhexyl) phosphoric acid to the polymeric matrix, the N 1s signal intensities decrease, while the P 2p signal intensities increase with carrier concentration to a maximum corresponding to surface site saturation. Upon acid addition, the polyamide was protonated and an expected chemical shift of the N 1s signal to higher binding energies was observed due to the increase of the positive charge of the nitrogen atom. This type of chemical interaction allows to fix the carrier in the membrane without its complete immobilization. On the other hand, the surface concentration of N and P, determined by XPS, indicates that a concentration of 400 mM of the carrier in the casting solution is sufficient to saturate the surface of the membrane. Copyright 2000 Academic Press.     

在不同稀释剂中二（2—乙基己基）磷酸萃取Ni（Ⅱ）原热力学

研究了在不同稀释剂如苯，甲苯，正己烷，环己烷，四氧化碳，氯仿中萃取剂浓度，水相酸度以及温度对二（２－乙基己基）磷酸萃取Ｎｉ（Ⅱ）的平衡的影响，借助萃合物红外光谱，确定了萃合物组成和萃取反应机理。     

二-(2-乙基己基)磷酸与仲壬基苯氧基取代乙酸混合体系对稀土元素的萃取

考察了二-(2-乙基己基)磷酸(D2EHPA,H2A2)和仲壬基苯氧基取代乙酸(CA100,H2B2)混合体系在HCl介质中对15种镧系元素(除钷)及钇的萃取性能,计算了稀土元素间的分离系数,并比较了混合萃取体系与D2EHPA单独萃取体系对稀土元素的分离能力.研究了D2EHPA-CA100混合体系对镧的协同萃取机理,用斜率法和恒摩尔法探讨了萃取反应方程式,考察了酸度、萃取剂浓度及温度对萃取性能的影响.结果表明:D2EHPA-CA100混合体系对镧系元素的协同效应随原子序数的增加而减弱.在适当的萃取剂配比下,此混合体系对某些稀土元素的分离能力优于D2EHPA,可用于这些稀土元素的分离.D2EHPA-CA100混合体系协同萃取镧的萃合物组成为LaH5A6B2,反应为吸热反应.     

Extraction Mechanism of Uranium(VI) with Di(1-Methylheptyl)Phosphoric Acid

The extraction of U(VI) from nitric acid solutions with di-(1-methylheptyl) phosphoric acid has been investigated. The dependence on nitric acid concentration, DMHPA concentration and temperature has been considered and the infra-red spectra of extracted species and extractant were recorded. The mechanism of extraction is discussed in the light of the results obtained.     

Extraction Kinetics of Uranium(VI) with di(2-ethylhexyl) Phosphoric Acid Using a Hollow Fiber Membrane Extractor

The kinetics of solvent extraction of U(VI) with di(2-ethylhexyl) phosphoric acid (HDEHP) using a microporous hydrophobic hollow fiber membrane extractor has been investigated. The effects of U(VI) and hydrogen ion concentrations in aqueous phase, HDEHP concentration in organic phase, flow velocities of aqueous and organic phase and temperature on extraction rate of U(VI) were examined. The experimental results suggest that the extraction rate of U(VI) is controlled by diffusion.     

Carbohydrate Phosphorylation with Phosphoric Acid,Polyphosphoric Acid,Pyrophosphoric Acid,and Anhydrous Phosphoric Acid

Abstract

Pyrophosphoric acid was first reported as a phosphorylating agent for highmolecular weight alcohols in 1934¹. Direct phosphorylating of sugars and sugar derivatives was first carried out by Cherbuliez² who used polyphosphoric acid on alcohols, amines and glycols. These precedents suggested to Seegmiller and Horecker in 1951³ to try tetraphosphoric (polyphosphoric) acid, as supplied by commercs, as the phosphorylating agent of carbohydrate phosphorylation. Carbohydrates can be phosphorylated when all but one of the positions is blocked by suitable protective groups, or, on rare occasions, in the unblocked, “natural” stata.? The latter method can be used only on terminal, C₅ or C₆ positions as the 5-phosphates of pentoses and the 6-phosphates of hexoses are more stable at low pH than other phosphates and can withstand an acidic hydrolysis of the mixture of phosphorylated sugars resulting from such phosphorylation. For the phosphorylation of easily available, cheap pentoses and hexoses in the 5- and 6-positions respectively, with cheap polyphosphoric acid, this is the method of choice.     

“可乐”与磷酸

“可乐”亦称可口可乐,是一种软饮料(与含酒精的“硬”饮料相区别)。因起初由可乐豆提取汁配料制成而得名。“可乐”以其特有的臻予佳境的美味深受消费者青睐,盛行世界各国,尤其在青年学生中最为流行,其消费量在食品中占第一位。